81666410 has 16 divisors (see below), whose sum is σ = 167999616. Its totient is φ = 27999888.

The previous prime is 81666379. The next prime is 81666413. The reversal of 81666410 is 1466618.

It is a happy number.

It is not an unprimeable number, because it can be changed into a prime (81666413) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 583262 + ... + 583401.

It is an arithmetic number, because the mean of its divisors is an integer number (10499976).

Almost surely, 2^81666410 is an apocalyptic number.

81666410 is an abundant number, since it is smaller than the sum of its proper divisors (86333206).

81666410 is a wasteful number, since it uses less digits than its factorization.

81666410 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1166677.

The product of its (nonzero) digits is 6912, while the sum is 32.

The square root of 81666410 is about 9036.9469402005. The cubic root of 81666410 is about 433.8582114497.

The spelling of 81666410 in words is "eighty-one million, six hundred sixty-six thousand, four hundred ten".